This is actually interesting. It looks like Apple did not intentionally block hackint0sh netbooks but just screwed up on an update.
Given the fact they only have to test their OS on the hardware configurations they sell, it is not surprising that OSX would have some issues on the vast majority of untested hardware.
Now imagine the uproar if Microsoft pulled something like this. They can't afford it, because their OS HAS TO WORK on almost every x86 processor available, be it Intel, AMD or Via (and I'm not even counting video cards, sound cards, RAID cards, WiFi adapaters, etc.).
I think this illustrates how easy Apple has it compared to Microsoft when debugging and testing their OS. As more people strive to install OSX on a wider range of hardware, this is going to get more common.